Relational databases are mechanisms for storing and retrieving data based on a relational data model, which generally organizes data into one or more tables of rows and columns. Such relational databases generally employ a fixed schema or structure, which defines the tables and a relationship between the data contained in the tables. Non-relational databases are mechanisms for storing and retrieving data that are modeled other than in the tabular relational form. Such non-relational databases are schema-free (i.e., the data has no fixed schema or structure), and are generally capable of handling large volumes of data with high throughput and low latency relative to relational databases.